Generally, in semiconductor manufacturing processes, the TiN layer has been widely used as a diffusion barrier layer and adhesion layer. The TiN layer is commonly formed by two methods, one of which is the physical vapor deposition method (hereinafter, referred to as the PVD method) and the other of which is the chemical vapor deposition method (hereinafter, referred to as the CVD method). However, the CVD method has been generally used for forming the TiN layer because of the excellent step-coverage.
The TiN layer is made by pyrolyzing source materials such as tetrakisdimethlyaminotitanum (TDMAT) and tetrakisdiethlyaminotitanum (TDEAT), and the TiN layer is porous.
However, since the TiN layer made by pyrolyzing includes carbide and oxide, it has high resistivity of about 10.sup.4 .mu.ohm-cm or more. Also, when the TiN layer is exposed to the air, the TiN layer absorbs moisture and oxygen due to its porosity. In a case here the TiN layer is exposed for about twenty-four hours, the resistivity of an exposed TiN layer may be three and a half times higher than that of a TiN layer not exposed. Consequently, the quality of the TiN layer deteriorates.